1. Technical Field
This invention relates generally to vehicle lighting systems such as tail lights, signals, markers, emergency beacons and the like, and more particularly to such systems employing glow discharge gas as the illumination source.
2. Description of the Related Art
Incandescent bulbs are typically used in vehicle lighting systems, such as tail lights, signals, markers, and the like as the illumination source. The lamps contain a filament that glows white hot when sufficient current is passed through it. A major disadvantage of incandescent lighting is that the filaments are very fragile and short-lived and require periodic replacement to maintain the lights of the vehicle in working order. The problem of broken lamps is aggravated when the lamps are installed in vehicles which operate in abusive or rough terrain conditions, such as off-road vehicles, tractor/trailer rigs, construction and heavy equipment vehicles, etc.
Neon gas discharge lighting systems are known having an internal electrode contained within the sealed envelope of neon gas and driven by a high voltage ballast. The ballast operates to convert a relatively low voltage to high voltage sufficient to cause the electrode to arc and excite the gas to glow discharge. Such electrodes, however, are similarly fragile and prone to breakage and thus require periodic replacement. The ballast likewise has a limited service life and thus may also require periodic replacement. Moreover, the ballast draws considerably on the available power resource, which in the case of a vehicle are limited.
So-called "electrodeless" neon gas discharge lamps are generally known, wherein neon gas is sealed within an envelope and surrounded by an RF induction coil that, when energized, produces RF emissions that excite the neon gas to discharge illumination. See, for example, those disclosed in international published application Nos. PCT/GB97/00099 and PCT/GB97/01576. The fact that there is no internal drive electrode or filament makes an electrodeless neon gas discharge illumination source in principal an attractive candidate for vehicle lighting systems since they could be expected to last for the service life of the vehicle and would eliminate the need for costly replacement.
While it has been suggested to use electrodeless neon gas discharge lighting in vehicles and early prototypes have been made to demonstrate the concept, it is believed that the known prior developments, from a manufacturing and economic standpoint, would not be viable as a practical alternative to incandescent lighting. The known systems are cumbersome and departure in basic design from the current incandescent lighting systems wherein the incandescent lighting source is manufactures as a separate, self-contained unit apart from the light housing in which the light is installed. The early electrodeless gas discharge prototypes integrated the various components with the light housing structure such that the electrodeless light source was not separate and distinct from the light housing, but rather relied on the housing structure to support the components of the light source in working relation to one another.
Accordingly, it is not known in the prior art to provide a vehicle lighting assembly in which an electrodeless neon gas discharge source is constructed as a self-contained module or unit separate and distinct from the light housing, and it is believed that such would be a viable, practical alternative to present day incandescent lighting systems.
It is accordingly an object of the present invention to advance the art of vehicular lighting and electrodeless neon gas discharge lighting technology in a manner that makes such an alternative light source viable for vehicular lighting applications.